The invention pertains to a blind rivet-type clamping fastener which includes a deformable sleeve part, a drift part which may be inserted into the sleeve part and cooperates with the same at least during the setting process, and a drilling part.
One example of a known rivet fastener (German Patent No. C 4,003,373) includes a rivet sleeve as well as a rivet drift which may be inserted into said rivet sleeve. The rivet sleeve and the rivet drift cooperate with each other via a thread. The enlarged head stud of the rivet drift is pressed against one end of the sleeve by turning the rivet drift relative to the rivet sleeve, so that the one end of the sleeve is expanded. Although such rivet fasteners are able to produce an excellent connection, the drilling part is still present at the rear side of the fastening point.
According to a different known variation (U.S. Pat. No. A 4,293,258), the drill tip, which is in this particular instance fastened onto the rivet sleeve, is also present once the setting process has been concluded.
The fact that this is practically always the case with self-drilling rivets is additionally substantiated by a previously disclosed self-drilling rivet (German Patent No. A 2,548,860). This particular rivet is provided with a plate-like drilling part which is constructed as one piece together with a widened head stud of the drift part, which, in other words, means that said drilling part is also present after the setting of the rivet fastener.
These protruding drilling parts represent a substantial hazard, in particular if the rear side of such connections is freely accessible. Although the utilization of self-drilling blind rivets substantially shortens the setting process and thus also reduces the mounting costs, the problem of injuries due to the protruding drilling parts remains.